The present invention relates to a pressure-formed bamboo sheet or bar and a production process therefor.
For the purpose of prior art for production of a sheet from bamboo, for example, as shown in FIGS. 9(A)-9(F), a bamboo plate material is produced by cutting a bamboo 1 of a given size along the axial direction of the bamboo into a plurality of slices to form a plurality of long bamboo square bars 4, joining said bamboo square bars 4 together into a laminated bamboo sheeting 5, and cutting said bamboo laminated sheeting 5 in a proper thickness.
More specifically, bamboo 1 is cut in a proper length, as shown by FIG. 9(A). Next, the bamboo 1 is split in the radial direction into proper numbers of slices, as shown in FIGS. 9(B) and (C). Then, each of the slices is machined by cutting off the inner and outer faces thereof to form a long bamboo square bar 4 having a length a and a width b, as shown in FIGS. 9(D) and (E). Then, a plurality of the long bamboo square bars 4 are laminated to each other into a laminated bamboo sheeting 5, as shown in FIG. 9(F). Specifically, the long bamboo square bars 4 are joined together under pressure with their respective front and back faces 41 and 42 stuck to each other with adhesives. In the drawing, the numeral 43 designates the side of the long bamboo square bars 4, and 44 the end face of same, the bamboo fibers extending in a longitudinal direction (in the direction x). Finally, the laminated bamboo sheeting 5 is cut from above piece by piece in an equal thickness to obtain a bamboo plate material 6, as shown by a dotted line in FIG. 9(F). The resultant bamboo plate material 6 comprises slices 6' constituted by long bamboo square bars 4 connected with each other in the direction of width (in the direction y), with the bamboo fibers extending longitudinally (in the direction x), and the bamboo density changing widthwise (in the direction y). To be specific, the density is thicker at the side of front face 41, and more coarse at the side of back face 42.
With the bamboo plate materials, however, only a few parts of bamboo 1 can be used, while the other parts are thrown away. In addition, the processing of bamboo is complicated, and there is a limit to the promotion in the efficiency of production. Specifically, as shown in FIGS. 9(D) and (E), a machining operation takes place in the form of cutting off the inner and outer peripheries from a bamboo slice to form a long bamboo square bar 4 having a length a and a width b. The remaining bamboo parts left behind after forming the long bamboo square 4 are destined to be abandoned. And the processing involved in each procedure step is complex, such that the predetermined dimensions a, b must be secured at the step where a long bamboo square bar 4 is obtained. In addition, as shown in FIG. 9(F), the long bamboo square bars 4 must be laminated to one to another. In particular, irregularities in the dimensions a, b of each long bamboo square bar 4 is liable to give rise to gaps between the adjacent long bamboo square bars 4. Therefore, a resultant bamboo plate material 6 may also have such gaps formed therewithin so as to be imperfect as a plate-formed product. Furthermore, requiring a long bamboo square bar 4 with a predetermined length and width a and b from a hollow cylindrical bamboo makes it difficult to find and cut off a usable bamboo portion, and much of the long bamboo square bar 4 unavoidably goes to waste, as described above. Additionally, the fibers of resultant bamboo plate materials 6 may be irregular in density. While on the one hand, development of new uses for such products may be possible, these products will have restrictions in use.
Occasionally, some bamboo has eggs laid therein by insects harmful to bamboo. Although harmful insects can be exterminated from the bamboo using chemicals and drugs, laid eggs cannot possibly be exterminated completely. Thus after such egg-infested bamboo in question is processed into final products or after such products are sold, the eggs within the bamboo hatch, and the resulting insects eat away the bamboo from within to such an extent that the bamboo finally becomes porous.
An object of a first invention of the present application is to develop a pressure-formed bamboo product composed of bamboo materials which have reduced variations in fiber density, and which may be manufactured without using complicated processes and without losing of bamboo.
The object of a second invention of the present application is to develop a pressure-formed bamboo product composed of high-strength bamboo materials which are uniformly strong therethroughout with a reduced fiber density variation, and which may be manufactured without using any complicated process and without wasting of bamboo.
The object of a third invention of the present application is to provide a process for producing pressure-formed bamboo products while reducing waste, increasing the production efficiency for bamboo in more simple manner, decreasing bamboo fiber density irregularities, and effectively exterminating eggs of harmful insects from the bamboo.